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[gnulib.git] / lib / chown.c

diff --git a/lib/chown.c b/lib/chown.c
index 86dd371..b851cbc 100644 (file)
--- a/lib/chown.c
+++ b/lib/chown.c
@@ -1,11 +1,12 @@
 /* provide consistent interface to chown for systems that don't interpret
    an ID of -1 as meaning `don't change the corresponding ID'.
-   Copyright (C) 1997, 2004, 2005 Free Software Foundation, Inc.
 
-   This program is free software; you can redistribute it and/or modify
+   Copyright (C) 1997, 2004-2007, 2009 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -13,28 +14,29 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software Foundation,
-   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /* written by Jim Meyering */
 
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>
 
-/* Disable the definition of chown to rpl_chown (from config.h) in this
-   file.  Otherwise, we'd get conflicting prototypes for rpl_chown on
-   most systems.  */
-#undef chown
+/* Specification.  */
+#include <unistd.h>
 
+#include <stdbool.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#if HAVE_UNISTD_H
-# include <unistd.h>
-#endif
 #include <fcntl.h>
 #include <errno.h>
 
+/* Below we refer to the system's chown().  */
+#undef chown
+
+/* The results of open() in this file are not used with fchdir,
+   therefore save some unnecessary work in fchdir.c.  */
+#undef open
+#undef close
+
 /* Provide a more-closely POSIX-conforming version of chown on
    systems with one or both of the following problems:
    - chown doesn't treat an ID of -1 as meaning
@@ -44,7 +46,8 @@
 int
 rpl_chown (const char *file, uid_t uid, gid_t gid)
 {
-#if CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE
+#if HAVE_CHOWN
+# if CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE
   if (gid == (gid_t) -1 || uid == (uid_t) -1)
     {
       struct stat file_stats;
@@ -59,29 +62,48 @@ rpl_chown (const char *file, uid_t uid, gid_t gid)
       if (uid == (uid_t) -1)
        uid = file_stats.st_uid;
     }
-#endif
+# endif
 
-#if CHOWN_MODIFIES_SYMLINK
+# if CHOWN_MODIFIES_SYMLINK
   {
     /* Handle the case in which the system-supplied chown function
        does *not* follow symlinks.  Instead, it changes permissions
        on the symlink itself.  To work around that, we open the
        file (but this can fail due to lack of read or write permission) and
        use fchown on the resulting descriptor.  */
-    int fd = open (file, O_RDONLY | O_NONBLOCK | O_NOCTTY);
-    if (fd < 0
-       && (fd = open (file, O_WRONLY | O_NONBLOCK | O_NOCTTY)) < 0)
-      return -1;
-    if (fchown (fd, uid, gid))
+    int open_flags = O_NONBLOCK | O_NOCTTY;
+    int fd = open (file, O_RDONLY | open_flags);
+    if (0 <= fd
+       || (errno == EACCES
+           && 0 <= (fd = open (file, O_WRONLY | open_flags))))
       {
+       int result = fchown (fd, uid, gid);
        int saved_errno = errno;
+
+       /* POSIX says fchown can fail with errno == EINVAL on sockets,
+          so fall back on chown in that case.  */
+       struct stat sb;
+       bool fchown_socket_failure =
+         (result != 0 && saved_errno == EINVAL
+          && fstat (fd, &sb) == 0 && S_ISFIFO (sb.st_mode));
+
        close (fd);
-       errno = saved_errno;
-       return -1;
+
+       if (! fchown_socket_failure)
+         {
+           errno = saved_errno;
+           return result;
+         }
       }
-    return close (fd);
+    else if (errno != EACCES)
+      return -1;
   }
-#else
+# endif
+
   return chown (file, uid, gid);
+
+#else /* !HAVE_CHOWN */
+  errno = ENOSYS;
+  return -1;
 #endif
 }